1. Field of the Invention
The present invention relates to a zoom lens and an imaging apparatus. More specifically, the invention relates to the technical field of compact and high performance zoom lenses which can be advantageously used in imaging optical systems of digital input/output apparatus such as digital still cameras and digital video cameras and the technical field of imaging apparatus utilizing such zoom lenses.
2. Description of the Related Art
Recently, imaging apparatus such as digital still cameras using a solid-state imaging device has become popular. It is desirable to provide an imaging apparatus having further higher image quality as the apparatus such as digital still cameras are becoming popular. Particularly in the digital still cameras and so on, it is desirable to provide an imaging lens, especially a zoom lens, which has excellent focusing performance responding to a solid-state imaging device having a large number of pixels.
In addition to demand for higher image quality, demand for greater angles of view is becoming strong, and it is desirable to provide a compact zoom lens having a great zoom ratio, for example, 4× or more, and having a great angle of view, for example, exceeding 38 deg in terms of half-angle of view.
There are various types of zoom lenses to be used in digital still cameras, and as the lens types which can be provided with a small size and a great angle of view, three-group zoom lenses formed by a first lens group having negative refracting power, a second lens group having positive refracting power, and a third lens group having positive refracting power, which are disposed in the order from an object side to an image side are known (for example, see JP-A-2004-61675 (Patent Document 1, JP-A-2007-212636 (Patent Document 2) and JP-A-2007-333799 (Patent Document 3).
Referring to Patent Document 1, a second lens group includes two positive lenses and one negative lens to thereby realize a high-performance and compact zoom lens having a zoom ratio of approximately 3×.
Referring to Patent Document 2, a second lens group includes four lenses of a first cemented lens formed by bonding a positive lens and a negative lens, and a second cemented lens formed by bonding a negative lens and a positive lens to thereby realize a high-performance zoom lens having a great angle of view in which a zoom ratio is approximately 3.4×.
Referring to Patent Document 3, a second lens group includes four lenses of a positive lens, a cemented lens formed by bonding a positive lens and a negative lens, and a positive lens to thereby realize a high-performance zoom lens having a great angle of view in which a zoom ratio is approximately 3.4×.